Yarn winding apparatus

ABSTRACT

A yarn traversing apparatus which includes a pair of oppositely rotating blades for respectively moving the yarn in opposite directions along a main guide edge in a medial portion of the yarn traverse stroke. An auxiliary yarn guide is mounted in each of the ends of the traverse stroke. The main guide edge and the auxiliary guide edges extend through the traverse plane from opposite sides thereof, and they are configured so that the main guide edge guides the yarn and controls its speed along the medial portion of the stroke and the auxiliary yarn guides guide the yarn and controls its speed in the end regions of the stroke. The yarn tension thereby can be maintained substantially constant along the full length of the stroke.

BACKGROUND OF THE INVENTION

The invention relates to a yarn winding apparatus having a yarntraversing system which includes a guide edge and a pair of oppositelyrotating blades for respectively moving the yarn in opposite directionsalong the guide edge. Such a yarn winding apparatus is known, forexample, from DE 34 04 303 A1; EP 120 216 A; DE 34 17 457 C2; DE 37 03731 A1.

In the yarn traversing systems of these yarn winding apparatus, theguide edge has the following function: the yarn entraining arms orrotary blades have a constant angular speed, but have between the strokeends a different guiding speed in the traversing direction, in which theyarn is to be reciprocated parallel to the package axis. The guidingspeed is dependent on the constantly changing angular position of therotary blades and, therefore, is sinusoidal. The main guide edgedeflects the yarn from the traversing plane such that these speeddifferences are compensated in desired manner. A correspondingconfiguration of the guide edge allows to accomplish that the traversespeed is constant between the stroke ends--i.e., apart from the shortreversal regions, in which the direction of movement is reversed.However, the configuration of the guide edge and the rotary blades alsoallows to predetermine desired laws of movement. In this connection, thetraversing plane is described as the tangential plane which extendsthrough the apex yarn guide and the subsequent rotating cylinder towhich the yarn advances. The apex yarn guide is arranged centricallyabove the traverse stroke. It is spaced apart from the rotating cylindersuch that the yarn is able to stand the yarn tension fluctuations whichresult from the traversing motion. These yarn tension fluctuationsresult from the fact that the yarn length between the apex yarn guideand rotating body changes continuously, i.e., increases and decreases,as a result of the traversing motion. The rotating body is generally acontact roll, to which the yarn advances, and about which the yarn loopspartially, so as to then advance to the package.

Yarn traversing systems of the prior art permit to reciprocate the yarnover a long traverse stroke, for example 250 mm, with only one rotor foreach direction of movement. As a result, however, it is necessary tocompensate for great differences in the guiding speed. For this reason,the guide edge extends, in particular in the central region of thetraverse stroke, far into the traversing plane, whereas it extends inthe region of the traverse stroke ends close to the traversing plane.Accordingly, the looping angle of the yarn on the guide edge is large inthe central region of the traverse stroke, and accordingly the loopingangle of the yarn on the guide edge is small in the region of the strokeends.

It is the object of the invention to avoid these great differences inthe looping angle, which also lead to different yarn tensions, and tothereby enable long traverse strokes.

SUMMARY OF THE INVENTION

The above and other objects and advantages of the present invention areachieved by the provision of a yarn traversing apparatus which comprisesmeans for reciprocating an advancing yarn transversely to its advancedirection over a predetermined traverse stroke and so as to define atraverse plane, and at least two guide arms mounted for rotation aboutclosely adjacent parallel or coaxial axes so that the rotating armsdefine closely adjacent parallel planes and the extremity of eachrotating arm is adapted to pass along the traverse plane. The arms arerotated in opposite directions so that one arm moves in a directiontoward one end of the traverse stroke and the other arm moves in theopposite direction and from the one end of the traverse stroke towardthe other end thereof. Also, a yarn guide rail is mounted on one side ofthe traverse plane and defines a main guide edge which extends in adirection generally parallel to the traverse stroke and through thetraverse plane in a medial portion of the yarn traverse stroke tothereby guide the yarn and control its traversing speed, and the mainguide edge does not extend through the traversing plane adjacent eitherof the end regions of the traverse stroke. In addition, an auxiliaryguide edge is mounted in each of the end regions of the traverse strokeand on the other side of the traverse plane, with the auxiliary guideedges each extending through the traverse plane so that in the endregions the auxiliary guide edges guide the yarn and control itstransverse speed.

The invention as described above allows the maximum looping angles whichnaturally occur in the region of the greatest deviation of the guideedges from the traversing plane to be considerably reduced. Preferred isan arrangement, in which the maximum looping angles are approximatelyidentical, so that the yarn tension remains within certain limits. Theadvantage of the invention is that an unacceptable decrease of the yarntension can be avoided in the end regions of the traverse stroke. In theknown yarn winding apparatus, it is necessary to select the yarn tensionso high that its does not fall below a minimum value even in the endregions of the stroke. This means on the other hand that the yarntension is relatively high in the central region of the traverse stroke.The invention, however, counteracts the tendency of the yarn tension tobe reduced in the end regions of the stroke, and permits the tension toremain above a minimum value even when a low yarn tension is selected.

In a preferred embodiment, the plane of the rotor axes and the mainguide edge are arranged with respect to the traversing plane such thatthe yarn defines a first looping angle as it moves across the medialportion of the main guide edge, and a second looping angle as it movesacross each of the auxiliary yarn guides, with the first and secondlooping angles being approximately the same.

When winding a multifilament yarn, it is necessary to produce thepackage such as to permit the yarn to unwind again from the package alsoat a high speed. This becomes possible in particular, when the yarn isdeposited on the package in closed form, i.e., as if it were a uniformsubstantially round body. The contrary thereof is that the individualfilaments, of which the yarn consists, are deposited on the package inthe form of a wide band. In this instance, there is the risk during theunwinding of the yarn, that the individual filaments belonging togetherdo not separate simultaneously and evenly from the wound surface. Theyarn unwinds unevenly and may lead to a yarn or filament breakage. Toavoid having the yarn deposited as a wide band, the planes defined bythe main guide edge and the auxiliary guide edges may be locatedupstream of and closely adjacent the planes defined by the rotatingguide arms. By this arrangement, the yarn is deposited on the package asa closed body--and not as a wide band consisting of individualfilaments. In particular, this arrangement avoids having the enlargementof the individual filaments, which has previously been caused bydirecting a strong air current toward the yarn, be undone and dissolved.

Prerequisite therefor--as well as in all other embodiments--is that thetwo guide edges are arranged very close to one another and to the rotaryplanes of the yarn entraining arms.

The plane of the main guide edge and the plane of the auxiliary guideedges may be disposed on opposite sides of the planes defined by therotating arms. This permits a particularly exact transfer of the yarnfrom one rotary blade to the other in the reversal regions, and avoidsthe engineering problem of the close arrangement of the guide edges.

Basically, it is possible to arrange the main guide edge on either sideof the yarn advancing plane. Preferred, however, is that the main guideedge extends between the plane of the advancing yarn and the plane ofthe rotor axes. This is of advantage in particular for the operation andthe threadup of the yarn.

As already earlier described, it is useful to arrange at least the mainguide edge--in direction of the yarn advance--upstream of the plane ofthe rotary blades. In this instance, the main guide edge covers therotary blades, when it is arranged simultaneously between the plane ofadvance and the plane of the rotor axes, thereby complicating a properrelative adjustment of the rotors. To avoid this, a construction may beemployed wherein each guide edge consists of a frame attached to themachine frame, which circumscribes a window. The portion of the frame,which extends into the traversing plane, forms the guide edge.Otherwise, the window is cut out so wide as to make visible primarilythe end regions of the traverse stroke, in which the yarn is transferredfrom the one rotary blade to the other.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, an embodiment of the invention is described withreference to the drawing.

In the drawing:

FIGS. 1 and 2 are side views of a conventional yarn winding apparatusshowing different yarn positions with respect to the traverse stroke;

FIGS. 3 and 4 are side views of an embodiment of the invention showingdifferent yarn positions along the traverse stroke;

FIG. 5 is a top view (schematic) of a yarn traversing system with a mainguide edge and auxiliary guide edges;

FIG. 6 is a top view of further embodiments; and

FIGS. 7(I) through 7(V) are side views of an embodiment showing severalphases of the traversing motion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Common to the embodiments of yarn winding machines illustrated in thepresent application is the following: a yarn advances via an apex yarnguide 13 to a yarn traversing system and thence to a contact roll 12.The yarn partially loops about contact roll 12, for example at 60°, andthen advances onto a package 16. The contact roll is in circumferentialcontact with package 16. The package 16 is formed on a paper or plastictube 15. The plastic tube 15 is placed on a spindle 14. The spindle 14is driven at a speed, which decreases in the course of the windingcycle. The control of the spindle drive occurs as a function of thespeed of contact roll 12, which is measured for this purpose. Thecontrol of the spindle or spindle drive occurs such that the speed ofcontact roll 12 remains constant. The yarn traversing system consists ofrotors 1 and 2, to which several yarn entraining arms--also named rotaryblades within the scope of the present application--are attached. Therotor 1 has, for example, two yarn entraining arms 3 and 4, each offsetrelative to the other by 180°. The rotor 2 has yarn entraining arms 5and 6, likewise offset relative to one another by 180°. The rotors arearranged such that the yarn entraining arms 5 and 6 on the one hand, and3 and 4 on the other rotate in two closely adjacent planes of rotationparallel to one another. At the same time, however, the rotor axes, asshown in FIG. 5, are arranged eccentrically along a line which isparallel to the axis of the yarn package.

The rotors are driven in opposite direction of rotation and at 90°out-of-phase. If each of the rotors has, for example, three yarnentraining arms, same will be offset relative to one another by 120°.The rotary blades 3-6 guide the yarn along a guide edge 9 (main guideedge). Along each path, the yarn is guided by a rotary blade of the onerotor. At the stroke ends, this rotary blade moves below the guide edge,and the guidance of the yarn in the opposite direction is then takenover by one of the rotary blades of the other rotor, which emerges atthis moment from below the guide edge. Such a yarn traversing system isdescribed, for example, in EP-C 114,642.

Each of rotors 1 and 2 of FIG. 5 comprises two yarn entraining arms 3and 4 or 5 and 6 offset relative to one another by 180°. Yarn entrainingarm 5 of rotor 2 is currently in control of guiding the yarn, and guidesthe yarn to the left. At the end of the traverse stroke, it delivers theyarn to the oncoming arm 3 of oppositely rotating rotor 1. Main guideedge 9 extends with a certain profiling into the traversing plane, whichis here indicated as line 10. This means: the yarn advances from thedirection of the viewer, and the traversing plane extendsperpendicularly to the plane of the paper. Arranged in the region of thetraverse stroke ends are auxiliary guide edges 11 extending in twoplanes, which are closely adjacent to both the planes of rotation of theyarn entraining arms and relative to one another. The main guide edgeextends into the traversing plane from the same side as the yarnentraining arms. The auxiliary guide edges 11 extend into traversingplane 10 from the opposite direction.

The yarn winding apparatus of the prior art (FIG. 1) now shows that mainguide edge 9 in FIGS. 1 and 2 deflects the yarn from traversing plane 10shown in dashed lines, both at the end of the traverse stroke(illustration of FIG. 1) and in the center of the traverse stroke(illustration of FIG. 2).

As shown in FIG. 2, this results in a very considerable looping of theyarn on the main guide edge in the central region of the traversestroke. In the end regions, as shown in FIG. 1, only a very slightlooping is left. This change in the looping entails also a correspondingchange of the yarn tension, under which the yarn advances to contactroll 12 or package 16. In the end regions, as shown in FIG. 1, the yarnis no longer or only slightly deflected from traversing plane 10. Thisdeflection, as shown in FIG. 2, is very great in the central region ofthe traverse stroke. This deflection causes a high yarn tension, sincethe yarn is advanced from a feed system at a fixed speed, and thereforeany deflection is converted into a corresponding elongation and increaseof the yarn tension. On the other hand, the yarn tension in the endregions should be sufficient to permit a troublefree winding operation.Consequently, the yarn tension is all the higher in the central region,and it cannot always be avoided that the yarn tension in the centralregion exceeds the limit of impairment.

In contrast to this, remedial measures are taken in the embodiments ofFIGS. 3 and 4, as well as 6 and 7(I) through 7(V).

As seen in FIGS. 3 and 4 showing the first embodiment of the presentinvention, the main guide edge 9 is removed from the traversing planelikewise shown in dashed lines so far that at the traverse stroke ends(FIG. 3), main guide edge 9 does no longer extend into the traversingplane. Rather, at this point, auxiliary guide edges 11 extend from theopposite side into the traversing plane, and at the traverse stroke endsthey take over the guidance of the yarn. The auxiliary guide edges 11also provide for compensation of the guiding speed of the yarnentraining arms in the sense of a desired course of the traversingspeed, as well as the compensation for the looping angle, which is loston the main guide edge. They also provide compensation for thedeflection of the yarn from traversing plane 10. As is shown in FIGS.3-5, main guide edge 9 and auxiliary guide edge 11 overlap in the endregions of the stroke. As shown in FIG. 5, the auxiliary guide edgestake over the guidance approximately or preferably, when viewed from thecenter of the traverse stroke, somewhat before the intersection oftraversing plane 10 with main guide edge 9. This allows to accomplishthat the looping angles are approximately identical on the main andauxiliary guide edges.

As shown in FIGS. 6 and 7(I) through 7(V), it is not absolutelynecessary to arrange main guide edge 9 and auxiliary yarn guides 11 suchthat an overlapping occurs (viewed in the yarn direction). Rather, therelative arrangement of the guide edges is dependent on the entiregeometrical arrangement of the yarn path, traversing system, contactroll, and package.

In FIG. 6, the individual phases are indicated by dashed lines I-V.FIGS. 7(I) through 7(V) the same yarn winding apparatus in differentphases I-V of the traversing motion one following the other in directionof the arrows. Shown in FIG. 7(I) is the situation in the center of thetraverse stroke. Rotary blade 4 guides the yarn while it is deflected bymain guide edge 9. In phase II, the yarn has already entered into theguide slot between main guide edge 9 and auxiliary guide edge 11 in theend region of the traverse stroke. In this phase, auxiliary guide edge11 contacts the yarn for the first time. In phase III, as can be noted,the yarn is deflected by both the main guide edge and the auxiliaryguide edge. As a result, the looping angle remains substantiallyconstant.

In phase IV, the main guide edge is completely retracted from thetraversing plane. The yarn is now exclusively guided by the auxiliaryguide edge. Phase V shows the end of the traverse stroke. The yarn istransferred from the one rotary blade 4 of the one rotor to the otherrotary blade 6 of the other rotor. Likewise in this phase V, theauxiliary guide edge is exclusively in control of guiding the yarn indirection of the traverse.

A further characteristic of the embodiment of FIGS. 6 and 7(I) through7(V) is that main guide edge 9 and auxiliary guide edges 11 are arrangedin closely adjacent, parallel planes preceding the planes of the rotaryblades. This arrangement allows to accomplish that the yarn does notdisintegrate into its individual filaments when being raised fromcontact roll 12 or the package. Rather, the yarn is deposited as aclosed filament bundle on the package and, consequently, also againwithdrawn as a closed filament bundle when being unwound from thepackage. The described rotary blade type traversing system makes itnecessary to accurately adjust the rotary blades on the rotors, so thatthe yarn is transferred from the one rotary blade to the other at acertain point. To this end, one must be able to observe the rotaryblades. For this purpose, a window 17 in the main guide edge and windows18 in the auxiliary guide edges are used. The guide edges are thereforeconstructed as frames which each leave space for a window.

We claim:
 1. A yarn traversing apparatus comprisingmeans forreciprocating an advancing yarn transversely to its advance directionover a predetermined traverse stroke and so as to define a traverseplane, at least two guide arms mounted for rotation about closelyadjacent parallel or coaxial axes so that the rotating arms defineclosely adjacent parallel planes and the extremity of each rotating armis adapted to pass along the traverse plane, means for rotating each ofthe arms in opposite directions so that one arm moves in a directiontoward one end of the traverse stroke and the other arm moves in theopposite direction and from the one end of the traverse stroke towardthe other end thereof, a yarn guide rail mounted on one side of thetraverse plane and defining a main guide edge which extends in adirection generally parallel to the traverse stroke and through thetraverse plane in a medial portion of the yarn traverse stroke tothereby guide the yarn and control its traversing speed, and wherein themain guide edge does not extend through the traversing plane adjacenteither of the end regions of the traverse stroke, and an auxiliary guideedge in each of the end regions of the traverse stroke and mounted onthe other side of the traverse plane, with the auxiliary guide edgeseach extending through the traverse plane so that in the end regions theauxiliary guide edges guide the yarn and control its transverse speed.2. The yarn traversing apparatus as defined in claim 1 wherein the yarndefines a first looping angle as it moves across the medial portion ofthe main guide edge, and a second looping angle as it moves across eachof the auxiliary guide edges, and wherein the first and second loopingangles are approximately the same.
 3. The yarn traversing apparatus asdefined in claim 1 wherein the main guide edge defines a first planewhich is parallel to the planes of the rotating guide arms, and theauxiliary guide edges define a second plane which is parallel to theplanes defined by the rotating guide arms, and wherein the first andsecond planes are upstream of the planes defined by the rotating guidearms and closely adjacent to each other.
 4. The yarn traversingapparatus as defined in claim 1 wherein the main guide edge defines afirst plane which is parallel to and on one side of the planes definedby the rotating guide arms, and wherein the auxiliary guide edges definea second plane which is parallel to and on the opposite side of theplanes defined by the rotating guide arms.
 5. The yarn traversingapparatus as defined in claim 1 wherein the means for rotating the twoguide arms define at least one rotational axis which is disposed on oneside of said traverse plane, and wherein said yarn guide rail is mountedon said one side of said traversing plane.
 6. The yarn traversingapparatus as defined in claim 1 wherein said yarn guide rail is in theform of an open framework which defines a window for facilitating theviewing of the rotating guide arms.